I have post this idea somewhere in this forum, but it's ok, I'll repeat again and add it with more ideas. And sorry for my bad english
Personalize your equipments
Right now, we have already two version of weapons and armors. cutting and blunt weapon, and light and heavy armor. My idea is to personalize these equipment to give them more tactical & strategic value to each units.
Cutting weapon has more damage than blunt weapon, but blunt weapon can damage heavy armored units more effectively
Heavy Armor has more defence point than Light Armor, but it decrease both of strategic & tactical speed by a numbered point.
This way, you can cut light armor more effectively by cutting weapon while need blunt weapon to destroy heavy armored one.
Then, I add pierce weapon like Spear and bow. These weapon can destroy heavy and light armor more effectively than cutting and blunt weapons. The only counter for pierce weapon is shield
By this weapon array, I can create lot of different units and combine them as one effective army.
For example, I can create a formation of 2 heavy armored with shield infantry, 2 spear infantry, and 1 heavy cavalry, and 1 archer unit
I can create formation by putting my heavy armored infantries to the front lines, while my spear to the second lines. After that, I can put my archers at the last lines while my cavalry on the right side of the battlefield.
If the game apply additional rules that make the archer to attack the back lines formation, I can use my Heavy Infantry to protect my others units from the enemy archers when my army move forward. Then, after the two armies meet together in melee combat, My H. Infantry can step aside and let my spear to attack the enemy centre lines. Because the spear is good against both armors, then I can hit more damage to the enemy while my H. Infantry protect the flank. Or, if the enemy has shielded units at the centre, I can move my spears to the flank, attack the enemy second lines with my spears.
Also, with H. Cavalry (heavy armored soldier with a horse), I can pass the enemy front line and attack their archers.
From the strategy map, I can create light Cavalries. Fast moving horsemen who can avoid enemies main army and attack the weak / non protected enemy cities. With this cavalry, I can attack a city, raze them, and run. (it is the tactic of Mongol). Make a confusion to the enemy rank. Break their formation to protect their whole teritories. When their army splited, I use my main army to break through the enemy line and destroy their capital city.
Because of the lack of horses on the the global resource, owning a horse resource will give you a lot of advantage, thus make the enemy to target your horse resource to balance the power. Then, you can protect your strategic resource (horse) by putting some archers here. Because archery has pierce attack, then the enemy need shielded troop to graps the resource. Etc etc etc
With the different strategic map point that added to the armor (Heavy armor reduce the unit overall speed), the terain become more meaningful than before. For example, You don't have iron, then you create light infantry (that only use material and not Iron). Thus, you can put your army to the jungle / forest. When the enemy heavy Infantry come, you can use the forest as your combat stage, lure the enemy heavy infantry to the jungle, reduce their effectiveness in speed, and give you a lot of manouver advantage with light units.
Look at that, by only personalize your equipment has give the players a lot of option to destroy the AI; give you a lot of tactical choice and make the Unit design a lot of meaning.